System Configuration Data Handling Behavior

Status of This Memo

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This Internet-Draft will expire on 24 December 2021.¶

Copyright Notice

Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved.¶

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.¶

Table of Contents

1. Introduction

The NETCONF protocol [RFC6241] defines ways to read configuration and state data from a NETCONF server.¶

In some cases, a client-configured data item refers to a system generated data item (e.g., the auto-created interfaces "eth1"), which is only present in the <operational> datastore [RFC8342]. In order for it being referenced, the duplicated system configured data item needs to be retrieved from <operational> and overridden by the client.¶

In some other cases, a system generated configured data item is in the when/must statement, the similar operation should also be performed to make sure a successful validation, which is cumbersome.¶

Furthmore, when the system generated data item gets updated, there is no way to synchronize the update into <running> and the client can't detect the update automatically.¶

This document defines a "system" datastore to hold all the configurations provided by the system itself. It also defines a capability-based extension to the NETCONF protocol that allows the configuration synchronization between <system> and <running> both automatically and explicitly.¶

3. System Configuration data handling Basic Modes

Not all server implementations treat system configuration data in the same way. Instead of forcing a single implementation strategy, this document allows a server advertise a particular style of system configuration data handling, and the client can adjust behavior accordingly.¶

This document specifies two standard system configuration handling basic modes that a server implementor may choose from:¶

• auto-populate¶
• no-populate¶

A server that uses the 'auto-populate' basic mode MUST automatically¶

• Update <running> with the system configuration change, after the "system" configuration has been altered as a consequence of a plug and play operation or device powering on operation. However the configurations in <running> can not be removed automatically when configuration data nodes in <system> is deleted since those configurations in <running> are likely to have already been modified or referenced.¶
• The system configuration doesn't need to be explicitly set by the client first before the system configuration needs to be updated with client set configuration or referenced by client set configuration.¶

A server that uses the 'no-populate' basic mode¶

• MUST not update <running> with the system configuration.¶
• The system configuration MUST be explicitly set by the client first before the system configuration needs to be updated with client set configuration or referenced by client set configuration.¶

6. YANG Module

This YANG module uses the "datastore" identity [RFC8342]. Every NETCONF server which supports :with-system capability MUST implement this YANG module.¶

<CODE BEGINS> file="ietf-netconf-with-system@2021-05-14.yang"
 module ietf-netconf-with-system {
    yang-version 1.1;
    namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-with-system";
    prefix ncws;

    import ietf-datastores {
    prefix ds;
    reference
      "RFC 8342: Network Management Datastore Architecture(NMDA)";
    }

    organization
     "IETF NETCONF (Network Configuration Protocol) Working Group";

    contact
     "WG Web:   <http://tools.ietf.org/wg/netconf/>
      WG List:  <mailto:netconf@ietf.org>
      WG Chair:
      Editor:
                                                 ";
    description
     "This module defines an extension to the NETCONF protocol
      that allows the NETCONF client to control how system configuration
      data are handled by the server in particular NETCONF operations.

      Copyright (c) 2010 IETF Trust and the persons identified as
      the document authors.  All rights reserved.

      Redistribution and use in source and binary forms, with or
      without modification, is permitted pursuant to, and subject
      to the license terms contained in, the Simplified BSD License
      set forth in Section 4.c of the IETF Trust's Legal Provisions
      Relating to IETF Documents
      (http://trustee.ietf.org/license-info).

      This version of this YANG module is part of RFC XXXX; see
      the RFC itself for full legal notices.";
    // RFC Ed.: replace XXXX with actual RFC number and remove this note

    revision 2021-05-14 {
      description
        "Initial version.";
      reference
       "RFC XXXX: With-system capability for NETCONF";
    }

    feature system-datastore {
      description
        "Indicates that the system configuration is available as a datastore.";
    }

    identity system {
      if-feature "system-datastore";
      base ds:datastore;
      description
        "This read-only datastore contains the system configuration for the
         device that will be loaded into <running> automatically in the
         "auto-populate" basic mode.";
    }
 }

<CODE ENDS>

7. IANA Considerations

This document registers the following capability identifier URN in the 'Network Configuration Protocol Capability URNs registry':¶

urn:ietf:params:netconf:capability:with-system:1.0

This document registers two XML namespace URNs in the 'IETF XML registry', following the format defined in [RFC3688].¶

      URI: urn:ietf:params:xml:ns:netconf:system:1.0
      URI: urn:ietf:params:xml:ns:yang:ietf-netconf-with-system

   Registrant Contact: The NETCONF WG of the IETF.

   XML: N/A, the requested URIs are XML namespaces.

This document registers one module name in the 'YANG Module Names' registry, defined in [RFC6020] .¶

      name: ietf-netconf-with-system
      prefix: ncws
      namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-with-system
      RFC: XXXX // RFC Ed.: replace XXXX and remove this comment

8. Security Considerations

The YANG module specified in this document defines a schema for data that is designed to be accessed via network management protocols such as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446].¶

The Network Configuration Access Control Model (NACM) [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content.¶

9. Acknowledgements

Thanks to Robert Wilton, Kent Watsen, Balazs Lengyel, Timothy Carey for reviewing, and providing important input to, this document.¶

Authors' Addresses